In modern automatic and semi-automatic firearms, reloading is frequently accomplished by an ammunition storing and deploying component known as an ammunition magazine (“magazine”), which stores a series of ammunition cartridges that may be serially fed into the firearm chamber for firing. In some firearms, magazines are fixed to the firearm, meaning that they are not designed to be removed and replaced with other magazines rapidly by a standard user operation during use of the firearm, and/or without separate tools. Some firearms implement detachable magazines, which, by contrast, may be removed and replaced during firearm use by a standard user operation during use of the firearm, without separate tools.
Firearms used in combat and other situations with potentially heavy crossfire often incorporate detachable magazines, because the serial reloading of cartridges into a fixed magazine would require too much time during use of the firearm and jeopardize the safety of the user. In such situations, a user may carry several fully loaded, detached magazines to rapidly, fully reload the firearm during engagement. Firearms using fixed magazines are better adapted to sporting or remote use (such as hunting or sniping), but even in those contexts, a detachable exchangeable magazine firearm is often used.
Both detachable and fixed magazines are typically rectangular or curved (in the instance of “banana” style clips) boxes, incorporating a spring that applies force to a movable piece called a “follower” attached to the spring, for feeding cartridges into a firing chamber, seriatim, from a magazine port, which typically has a lip (or lips) partially closing it for the retention of the cartridges until they are fed into the firing chamber. A bolt or other feeding and/or firing mechanism action may enter an open part of the port to catch an edge of, and push, a cartridge through another more open part of the port, sliding it out of the magazine and into the firing chamber (after removing a shell casing from the firing chamber, if necessary). But magazines may take a wide variety of other forms, including cylindrical shapes, without springs and followers. See, e.g., U.S. Pat. No. 6,502,495. Typically, when a magazine has been emptied by use of the firearm, a last, remaining bullet may still occupy the firing chamber, until it is fired. In some magazine systems, firing that final cartridge will result in the bolt and/or action being “locked open” to signify that the magazine is empty and requires reloading or replacement. See id.; see also U.S. Pat. No. 708,794, to Browning (patent for the Colt Model 1902, which included last shot hold-open) (claim 3).
In some magazine systems, the magazine may at least roughly indicate the amount of ammunition remaining loaded in a magazine, for instance, by a “window” or other indicator of the degree to which the magazine is filled with ammunition or the degree to which the follower and/or spring have risen in the magazine due to the removal of ammunition. See, e.g., Product Literature re: CAA Tactical's Mag 17, available at http://www.caatactical.com/viewProduct.asp?ID=351&catID=318, accessed Sep. 17, 2012.
A wide variety of magazine stowing and deployment easing solutions have also been invented, such as belts, pockets, holsters and grips. Such systems may aid soldiers and other firearms users in accessing and replacing magazines. See, e.g., U.S. Pat. No. 6,481,136.